Lifting clamp



Augl5, 1967 R. L.. RENFROE 3,336,068

LIFTING CLAMP Filed June l5, 1965 5 Sheets-Sheet l INVENTOR- /6/ J u Rayma/zd L. Rerz'rae ATTORNEYS Aug.15,1967 RLRNFROE l3,336,068

` LIFTING CLAMP Filed June l5, 1965 5 Sheets-Sheet 2 6.6 :1E: l f3@ Z :641 l j /Z j I E 5g INVENTOR 'I H j Raymond L. Ren/0F06 50 49/ BmMMM@ ATTORNEYS Aug. 15, 1967 R; L. RENFROE 3,336,068

LIFTING CLAMP Filed June l5, 1965 5 Sheets-Sheet 3 INVENTOR Raf/mand L. Rerzrae A'IT RNEYS Aug. 15, 1967 R. RENFROE 3,336,068 LIFTING CLAMP Filed June 15, 1965 5 Sheets-Sheet INVENTOR Rymom L. Re/zfroe ORNEYS United States Patent O Fla., assignor to Inc., Jacksonville, Fla., a corpo- This invention relates to clamps for use with structural members and more particularly to clamps used for lifting or sorting structural members.

Conventionally, lifting clamps are designed to perform either vertical type lifting (the lifting of a vertical article) in which one clamp is placed on the article to be lifted and it is lifted directly upward with the lifting force acting inwardly of the slot in -the clamp or it is designed for horizontal lifting (the lifting of a horizontal article) in which two clamps Work in a pair to lift the article with the lifting force acting outwardly of the slots of the clamps. The use of two different types of clamps to perform these different types of lifting has necessitated the frequent changing of clamps on the lifting cables and requires that both types of clamps be kept on hand. Additionally, in many conventional clamps, the lifting force must be applied in one direction only. They can not easily rotate an article from a horizontal position to a vertical position for lifting and again rotate the article from the vertical position to the horizontal position when it is being deposited in a selected location.

The pending application of Josh L. Renfroe, Ser. No. 464,135, filed June 15, 1965, is directed to a clamp in which the lifting force may be applied in either direction parallel to the slot of the clamp or vertically with respect to the slot. This clamp accomplishes both horizontal and vertical lifting and rotates objects from horizontal to vertical position. The present invention is an improvement over that shown in such application wherein the lifting cable is required to be in the immediate area of the jaw and may engage the article being lifted when the lifting force is applied parallel to and outwardly of the slot. Additionally, the amount of gripping force applied to the article being lifted varies substantially with the direction of the lifting force. Thus, when the lifting force is acting outwardly of the slot, the gripping force may be much greater than the gripping force applied to an article in the slot when the lifting force is acting inwardly of the slot or vertically with respect to the slot.

It is therefore a primary object of this invention to provide an improved horizontal-vertical lifting clamp.

It is a further object of this invention to provide an improved horizontal-vertical lifting clamp giving a more constant gripping force regardless -of the direction of the lifting force.

It is an additional object of this invention to provide an improved lifting clamp which may be used very effectively for torque lifting. Y

Additional objects and advantages will become readily apparent to those skilled in the art from the following description and drawings.

Generally the invention which accomplishes the above objects and purposes may be described as a lifting Clamp capable of gripping structural articles when the lifting force is applied in any of a plurality of directions comprising a hook shaped clamp body having a horizontal slot therein, a jaw assembly pivotally mounted in said clamp body above the slot, said jaw assembly including a first pivot pin mounted in said body and a jaw mounted on said 1irst pivot pinY and having a gripping edge movable into a gripping relation with an article in the slot, abutment means mounted on said body and spaced from iirst pivot pin; a second pivot pin mounted on said jaw ICC and spaced from said irst pivot pin, said first pivot pin being positioned between said gripping edge of said jaw and said second pivot pin, a generally upright shackle pivotally connected at its lower end to said jaw by said second pivot pin so that a lifting force applied to said shackle either vertically away from said slot or horizontally in either direction parallel to said slot pivots said jaw about said lirst pivot pin to bring said jaw into gripping relation with an article in the slot, said shackle being positioned between said first pivot pin and said abutment means and having a bearing surface for engaging said abutment means to cause said shackle to move said jaw to the gripping relation when the lifting force is applied parallel to the slot in a direction which urges said shackle away from said first pivot pin and against said abutment means.

Preferably the bearing surface of the shackle comprises a 4cam surface to permit the shackle to slide along the abutment. The clamp may also have a locking means connected to the jaw to bring the jaw into an initial gripping relation prior to the application of the lifting force to the shackle. The clamp may also have a handle means attached to the side of the body opposite the slot for ease in placing the clamp on the structural articles.

It is also preferred that the shackle have a bearing surface for engaging the jaw assembly when said shackle is pivoted toward said jaw assembly to permit said shackle to move the jaw to the gripping relation with an article in the slot when the lifting force is applied parallel to the slot in a direction which urges said shackle against said jaw assembly.

The invention having been generally described, the preferred specific embodiments will be described -in detail with reference to the accompanying drawings in which:

FIGURE 1 is a top plan View of a lifting clamp constructed in accordance with the invention;

FIGURE 2 is a front elevation of the lifting clamp of FIGURE 1 mounted on the end of an I-beam;

FIGURE `3 is a Vertical section taken along line 3-3 of FIGURE 1;

FIGURE 4 is an inclined section taken along line 4-4 of FIGURE 3 showing the handle of the locking means;

FIGURE 5 is an end View of the clamp illustrated in FIGURES 1-4;

FIGURE 6 is a top planview of a modified lifting clamp constructed in accordance with the invention;

FIGURE 7 is a vertical section taken along the line 7 7 of FIGURE 6;

FIGURE 8 is an end View of the clamp illustrated in FIGURES 6 and 7;

FIGURE 9 is a front elevation showing a pair of clamps according to the invention used to lift a horizontal I-beam; and

FIGURE l0 is a perspective view of a pair of clamps according to the invention used t-o lift a vertical plate by a torque action.

Referring now to the drawings, the clamp 10 has a hook shaped body 11 as shown in FIGURE 2. The body 11 is comprised of a pair of aligned hook shaped body plates 12 and 14 respectively, held in position by a body spacer plate 16 and a body pin 18. The plate 16 and pin 18 are welded yor otherwise securely aiiixed to the insides of plates 12 and 14. Each of plates 12 and 14 has a horizontal opening forming a horizontal slot 20 in the clamp body for receiving a structural article. The spacing between plates 12 and 14 provides a vertical slot 22 (FIG- URE 5) in the body of the clamp through which the webs of I-beams and the like may extend.

Although the slot 20 is defined as horizontaL it is only horizontal when the clamp is in one normal reference position. The description of the position of the parts with respect to one reference position of the clamp is merely a convenient expedient to show the relative positions of all parts.

A jaw assembly 24 is pivotally mounted on the body on one side of the slot 20. As here embodied, the jaw assembly 24 is mounted between plates 12 and 14 at a position above horizontal slot 20. The jaw assembly 24 includes a cam jaw 26 and a pivot pin 30 pivotally mounting jaw 26 between plates 12 and 14. The jaw 26 has serrations 28 formed on the lower end thereof to provide a gripping surface to grip the structural article to be lifted.

A shackle 32 having a lifting connection eye 34 is pivotally mounted on the jaw assembly 24 by a pivot pin 36. Pivot pin 30 is positioned between and spaced from gripping edge 28 of jaw 26 and pin 36. Shackle 32 is bifurcated, having a pair of legs 38 and 40 (FIGURE 5) which straddle jaw 26 with pivot pin 36 extending through the two shackle legs and through jaw 26. Legs 38 and 40 of shackle 32 extend into the body of the clamp between the side plates 12 and 14 and have a sliding engagement therewith.

The edges of legs 38 and 40 which are adjacent pivot pin 30 are recessed to permit the shackle to be pivoted toward jaw 26 without engaging pivot pin 30. The edges of legs 38 and 40 which are adjacent body pin 18 are recessed to form a curved cam surface lto permit shackle 32 to slide up along body pin 18 when the lifting force is acting in a direction which urges the shackle toward body pin 18. The body pin 18 serves as an abutment limiting outward movement of the shackle 32 and as a fulcrum about which the shackle rotates outwardly to apply an upward force to the pin 36.

Locking means are provided to lock the cam jaw in a gripping relation with an article in horizontal slot 20. Jaw 26 has a pair of slots 44 and 46 (FIGURE 3) formed in one side thereof. A lock release handle, generally 48, consisting of an arm 50 extending generally perpendicularly from a sleeve 52 is mounted outside of the clamp body on pivot pin 30 by a split locking pin 60. The inner end of sleeve 52 has a pair of projecting lugs 62 and 64 which engage slots 44 and 46 respectively of jaw 26. A coil spring 66 is mounted on a pin 68 extending between body plates 12 and 14. Spring 66 is coiled around pivot pin 30 on one side of jaw 26, extends over the top of jaw 26 and then is coiled around sleeve 52 on the other side of jaw 26. The spring thus exerts a constant downward pressure on jaw 24 urging it into slot 20 and thus into engagement with structural articles placed in slot 20. Since lugs 62 and 64 of handle 48 are engaged with slots 44 and 46, the jaw 26 may be manually pivoted out of slot 20 by an upward pressure on handle 48. At all other times the lock functions as a constant pressure lock with the pressure of spring 66 constantly urging jaw 26 into slot 20.

In use the clamp is placed on the structural article to be lifted with a portion of the article extending into horizontal slot 20. The operator lifts up on handle 50 of the locking means to move the jaw out of the slot 20. With the clamp positioned on the article to be lifted, the operator releases the handle 48 of the locking means allowing cam jaw 26 to be pivoted into gripping relation with the article in the slot by the force of spring 66.

The lifting force is then applied to shackle 32 as by a lifting cable or the like connected to eye 34 of the shackle. This lifting force urges jaw 26 into a firm gripping relation with the article in the slot. If the lifting or moving force is applied parallel to horizontal slot 20 in a direction outwardly of the slot as indicated by arrow A in FIGURE 2, the force will tend to cause shackle 32 to pivot about pin 36 into contact with body pin 18. The cam surface of the legs 38 and 40 of shackle 32 causes shackle 32 to ride up along body pin 18 lifting pivot pin 36 upwardly and pivoting jaw 26 about pivot pin 30 to urge the serrated 4- edge 28 of the jaw into a firm gripping relation with an article in the slot.

If the lifting force is applied parallel to horizontal slot 20 in a direction inwardly of the slot as indicated by arrow B in FIGURE 2 the shackle will pivot about pin 36 until the surface of shoulder 42 of shackle 32 engages the jaw 26 and urges the gripping surface 28 into a firm gripping relation with an article in the slot 20. If there is any upward component to the force acting in this direction, that is, if it is not exactly parallel to slot 20 but is slightly upward, the recessed surface on the edge of shackle 32 adjacent pin 30 will prevent the shackle from engaging pin 30 or jaw 26 and will permit the lifting force to move pin 36 upwardly and thus pivot jaw 26 about pin 30 into a gripping relation with an article in the slot. Thus it may be seen that because of the unique structure of this clamp, lifting forces may be applied to the shackle through `an arc of over 180 and the mechanical leverage acting on jaw 26 will be approximately the same. The lifting force applied to pin 36 will always be in an upward direction regardless of the direction of the force applied to the eye 34.

Illustrated in FIGURES 6-8 is a modified lifting clamp constructed in accordance with the invention. The clamp 110 includes a hook shaped body 111 which comprises a pair of hook shaped side plates 112 and 114 which are connected together by spacer plates 116 and 118 which are welded or otherwise connected to the plates 112 and 114. Each of the plates 112 and 114 has a horizontal opening which together define a horizontal slot 120 in the clamp body for receiving a structural article. The spacing between plates 112 and 114 provides a vertical slot 122.

A jaw assembly 124 is pivotally mounted on the body on the upper side of the slot 120. The jaw assembly includes a cam jaw 126 and a pivot pin 130 pivotally connecting the jaw 126 between the plates 112 and 114. The jaw 126 has a plurality of serrations 128 formed on the lower end thereof to provide a gripping surface to grip the structural article to be lifted.

A shackle 132 having a lifting connection eye 134 is pivotally mounted on the jaw assembly by a pivot pin 136. Pivot pin 130 is positioned between and spaced from gripping edge 128 of jaw 126 and and pin 136.

Shackle 132 is bifurcated, having a pair of legs 138 and (FIGURE v8) which straddle jaw 126 with pivot pin 136 extending through the two shackle legs and through jaw 126. Legs 138 and 140 of shack-le 132 extend into the body of the clamp between the side plates 112 and 114 and have a sliding engagement therewith.

The edges of legs 138 and 140 which are adjacent pivot pin 130 are -recessed to permit the shackle to be pivoted toward jaw 126 without engaging pivot pin 130. The edges of legs 138 and 140 which are adjacent spacer plate 118 are recessed to form a curved cam surface t0 permit shackle 132 to slide up yalong spacer plate 118 when the lifting force is acting in a direction which urges the shackle toward spacer plate 118. The upper end of the spacer plate 118 serves as an abutment 119 limiting outward movement of the shackle 132 and as a fulcrum about which the shackle rotates outwardly to apply an upward force to the pin 136.

Locking means are also provided to lock the cam jaw 126 in a gripping relation with an article in horizontal slot 120. A U-shaped lock lever 141 is pivotally mounted between the side plates 112 and 114 and is connected thereto by a pair of pivot bolts 142. Connected between a pin 143 near the outer end of lock lever 141 and an eyelet 144 connected to the cam jaw 126 is a tension spring 145. Connected to the extreme outer end of the lock lever 141 is a pull chain 146. As best seen in FIGURE 7, the lever 141 is in the locked position when it is rotated in a counterclockwise direction into engagement with the upper end of the spacer plate 16. In that position the axis of the spring 145 is below the axis of the pivot bolts 142 and 143. Thus, the locking lever and spring provide an overcenter lock.

When the lever 141 4is rotated from the 'locked position in a clockwise direction by the pull chain 146, as soon as the axis of the spring 145 passes above the axis of the pivot bolts 142, the lock snaps to an open position. When the lock is open, jaw 126 may be `freely pivoted about the pin 130. When the lever 141 is in locked position, a positive holding pressure is exerted against the jaw 126 urging it into the slot 120 and against a structural article to be lifted.

A handle 72 is Welded to the plates 112 and 114 at a position to the rear of spacer plate 116 on the opposite side of the clamp body from the open end of slot 120. The handle facilitates the mounting of the clamp on the structural article to be lifted. If desired, a similar handle may be employed on the clamp Shown in FIGURES 1-5.

The operation of the clamp 110 is identical to that of the clamp 10 previously described except for the different yfunction of the locking mechanism.

Typical uses for clamps according to this invention are shown in FIGURES 9 and 10. FIGURE 9 shows a pair of the clamps 110 being used to lift an I-beam horizontally with the flange of the I-beam extending into the horizontal slots of the clamps and the web of the I-beam extending through the vertical slots in the clamps. The lifting force being applied through cables 80 and 82 urges the shackles 132 against the spacer plates 118 and causes the shackle 132 to ride up the abutments on the spacer plates, thus urging the cam jaws into a firm gripping relation with the horizontal flange of the I-beam.

If desired, one of the clamps 110 may be employed in the same position on the I-beam to lift such beam with the latter in a vertical position. Thus, a lifting force applied to the shackle in a direction parallel to and away from the end of the beam will cause the shackle 132 to engage the cam jaw 126 and exert a closing force on the gripping surface 128.

Referring now to FIGURE l0, it may be seen that a pair of the clamps is being used to lift a vertical plate by torque action. rThe lifting force acting through cables 86 and 88 is parallel to the axis of the eyes of the shackles and is parallel to the plate being lifted. This lifting force tends to cant each clamp body providing a torque grip on the plate with the sides 0f the jaw on one side of the slot being urged upwardly and against the plate and the sides of the slot on the other side of the slot being urged downwardly and against the plate. The construction of the clamp which permits the shackle to remain at all times Within the -body of the clamp and to fill the space between the Ibody side plates allows this torque action to take place without breaking the shackle off of the clamp at pivot pin 36.

Many modifications and variations of this invention will become apparent to those skilled in the art without departing from the scope of 4the invention which is determined solely by the appended claims.

What is claimed is:

1. A lifting clamp capable of gripping structural articles when the lifting force is applied in any of a plurality of directions comprising:

a hook shaped clamp body having a horizontal slot therein, said slot having an inner base and an outer open end to permit insertion of an article in a direction extending from said openvend toward said base;

a jaw assembly pivotally mounted in said clamp body above the slot, said jaw assembly including a first pivot pin mounted in said body and a jaw mounted on said first pivot pin and having a .gripping edge movable into a gripping relation with an article in ythe slot;

abutment means mounted on said body and spaced from said rst pivot pin;

a second pivot pin mounted on said jaw and spaced 6 from said first pivot pin, said rst pivot pin being positioned between said gripping edge of said jaw and said second pivot pin, said first and second pivot pins and said abutment means extending transverse to said insertion direction;

a generally upright shackle pivotally connected at its lower end to said jaw by said second pivot pin so that a lifting force applied to said shackle either vertically away from said slot or horizontally in either direction parallel to said insertion direction pivots said jaw about said first pivot pin to bring said jaw into gripping relation with an article in the slot, said shackle being positioned between said first pivot pin and said abutment means and having a bearing surface for engaging said abutment means to cause said shackle to move said jaw to the gripping relation when the 'lifting force is applied parallel to said insertion direction in `a direction which urges said shackle away from said first pivot pin and against said abutment means.

2. The lifting clamp of claim 1 wherein said bearing surface of said shackle comprises a cam sur-face to permit said shackle to slide along said abutment.

3. The lifting clamp of claim 1 wherein locking means are connected to said jaw to bring said jaw into an initial gripping relation prior to the application of the .lifting force to the shackle.

4. The lifting clamp of claim 3 wherein said lock comprises spring means mounted on said body and bearing against said jaw to apply a constant pressure thereto to urge said jaw against an article in the horizontal slot, and a handle pivotally mounted on said first pivot pin and connected to said jaw to pivot said jaw out of said slot against the pressure of said spring.

5. The lifting clamp of claim 1 wherein a handle is attached to the opposite side of said clamp body from said slot to assist in the placing of the clamp on the structural article to be lifted.

6. A lifting clamp capable of gripping structural articles when the lifting force is applied in any of a plurality of directions comprising:

a hook shaped clamp body having a horizontal slot therein, said slot having an inner base and an outer open end to permit insertion of an article in a di-rection extending from said open end toward said base;

a jaw assembly pivotally mounted in said clamp body above the slot, said jaw assembly including a rst pivot pin mounted in said body and a jaw mounted on said first pivot pin and having a gripping edge movable into a gripping relation with an article in the slot;

abutment means mounted on said body and spaced from said first pivot pin;

a second pivot pin mounted on said jaw and spaced from said first pivot pin, said first pivot pin being positioned between said gripping edge of said jaw and said second pivot pin, said first and second pivot pins and said abutment means extending transverse to said insertion direction;

a lgenerally upright shackle pivotally connected at its lower end to said jaw by said second pivot pin so that a lifting force applied to said shackle pivots said jaw about said first pivot pin to bring said jaw into gripping relation with an article in the slot, said shackle being positioned between said first pivot pin and saidy abutment means and having on one side a first bearing surface for engaging said jaw assembly when said shackle is pivoted toward said jaw assembly to permit said shackle to move said jaw to the gripping relation with an article in the slot when the lifting force is applied parallel to said insertion direction in a direction which urges said shackle against said jaw assembly, said shackle having on its other side a second bearing surface -for engaging said abutment means to cause said shackle to move said jaw to the gripping relation when the lifting force is applied parallel to said insertion direction in a direction which urges said shackle against said abutment means.

7. The lifting clamp of claim 6 wherein said second bearing surface of said shackle comprises a cam surface to permit said shackle to slide along said abutment.

18. The lifting clamp of claim 6 wherein locking means are connected to said jaw to bring said jaw into an initial gripping relation prior to the application of the lifting force to the shackle,

9. The lifting clamp of claim 8 wherein said lock comprises spring means mounted on said body and bearing against said jaw to apply a constant pressure thereto to urge said jaw against an article in the horizontal slot, and a handle pivotally mounted on said first pivot pin and connected to said jaw to pivot said jaw out of said slot against the pressure of said spring.

10. The lifting clamp of claim 6 wherein a handle is attached to the opposite side of said clamp body from said slot to assist in the placing of the clamp on the structural article to be lifted.

11. A lifting clamp capable of gripping structural articles when the lifting force is applied in any of a plurality of directions comprising:

a clamp body having a pair of spaced generally hook shaped plates, the said plates being aligned so that their open ends form a horizontal slot in the clamp body, said slot having an inner base and an outer open end to permit insertion of an article in a direction extending from said open end toward said base;

a jaw assem'bly pivotally mounted in said clamp body above the slot, said jaw assembly including a first pivot pin mounted in said body and a jaw mounted on said rst pivot pin and having a gripping edge movable into a gripping relation with an article in the slot;

abutment means mounted on said body and spaced from said first pivot;

a second pivot pin mounted on said jaw and spaced from said first pivot pin, said first pivot pin being positioned between said gripping edge of said jaw and said second pin, said rst and second pivot pins and said abutment means extending transverse to said insertion direction;

a generally upright shackle pivotally mounted connected at its lower end to said jaw by said second pivot pin so that a lifting force applied to said shackle pivots said jaw about said first pin to bring said jaw into gripping relation with an article in the slot, said shackle being positioned between said first pivot pin and said abutment means and having on one side a first bearing surface for engaging said jaw assembly when said shackle is pivoted toward said jaw assembly to permit said shackle to move said jaw to a gripping relation with an article in the slot when the lifting force is applied parallel to said insertion direction in a direction which urges said shackle against said jaw assembly, said shackle having on its other side a second bearing surface for engaging said abutment means when said shackle is pivoted toward said abutment means, said second bearing surface of said shackle comprising a cam surface to permit said shackle to slide on said abutment means to move said jaw to the gripping relation when the lifting force is applied parallel to said insertion direction in a direction which urges said shackle against said abutment means;

locking means connected to said jaw to bring said jaw into an initial gripping relation prior to the application of a lifting force to the shackle; and

handle means attached to the opposite side of said clamp body from said slot to `facilitate the placing of the clamp on the structural article to be lifted.

References Cited UNITED STATES PATENTS 2,549,918 4/'1951 Miller 294-104 2,647,007 7/1953 Gmoser 294-101 X 3,163,457 12/1964- Renfroe 294-101 X HUGO O. SCHULZ, Primary Examiner. 

1. A LIFTING CLAMP CAPABLE OF GRIPPING STRUCTURAL ARTICLES WHEN THE LIFTING FORCE IS APPLIED IN ANY OF A PLURALITY OF DIRECTIONS COMPRISING: A HOOK SHAPED CLAMP BODY HAVING A HORIZONTAL SLOT THEREIN, SAID SLOT HAVING AN INNER BASE AND AN OUTER OPEN END TO PERMIT INSERTION OF AN ARTICLE IN A DIRECTION EXTENDING FROM SAID OPEN END TOWARD SAID BASE; A JAW ASSEMBLY PIVOTALLY MOUNTED IN SAID CLAMP BODY ABOVE THE SLOT, SAID JAW ASSEMBLY INCLUDING A FIRST PIVOT PIN MOUNTED IN SAID BODY AND A JAW MOUNTED ON SAID FIRST PIVOT PIN AND HAVING A GRIPPING EDGE MOVABLE INTO A GRIPPING RELATION WITH AN ARTICLE IN THE SLOT; ABUTMENT MEANS MOUNTED ON SAID BODY AND SPACED FROM SAID FIRST PIVOT PIN; A SECOND PIVOT PIN MOUNTED ON SAID JAW AND SPACED FROM SAID FIRST PIVOT PIN, SAID FIRST PIVOT PIN BEING POSITIONED BETWEEN SAID GRIPPING EDGE OF SAID JAW AND SAID SECOND PIVOT PIN, SAID FIRST AND SECOND PIVOT PINS AND SAID ABUTMENT MEANS EXTENDING TRANSVERSE TO SAID INSERTION DIRECTION; A GENERALLY UPRIGHT SHACKLE PIVOTALLY CONNECTED AT ITS LOWER END TO SAID JAW BY SAID SECOND PIVOT PIN SO THAT A LIFTING FORCE APPLIED TO SAID SHACKLE EITHER VERTICALLY AWAY FROM SAID SLOT OR HORIZONTALLY IN 